function fig = PlotRelaxationXe129(obj, t1relax)
    if nargin ==1 
        t1relax = obj.Xe129Relaxation;
    end
    
    dataR = t1relax.signal.getNodeData(1);
    dataPhase = t1relax.signal.getNodeData(2);
    fitting = t1relax.fitting.result;
    
    % Plot fit with data.
    fig = figure( 'Name', sprintf('Xe129 Relaxation [%s]', t1relax.timestamp), 'WindowStyle', 'docked'); 
    ax1 = subplot(2, 1, 1, 'Parent', fig);
    plot(ax1, dataR.x, dataR.y, 'b.-')
    xlabel(ax1, 'Time (s)'); ylabel(ax1, 'Signal (V)');
    grid on;
    ax2 = subplot(2, 1, 2, 'Parent', fig);
    plot(ax2, dataPhase.x, dataPhase.y/pi*180, 'b.', dataPhase.x, fitting(dataPhase.x), 'r-')
    xlabel(ax2, 'Time (s)'); ylabel(ax2, 'Phase (degree)');
    title(ax2, sprintf('Amplitude = %3.2f^{\\circ}, \\tau = %3.1f s', fitting.a, fitting.tau), 'Interpreter', 'tex');
    grid on;
end

